Lubrication of a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft

ABSTRACT

The invention relates to the lubrication of a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular walls that are radial with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising orifices for mounting the axes of said planet gears, and the cylindrical wall comprising through-holes for the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to the field of a mechanical reduction gears for turbine engines, in particular of an aircraft.

TECHNICAL BACKGROUND

The state of the art comprises, in particular, documents WO-A1-2010/092263, FR-A1-2 987 416, FR-A1-3 041 054, EP-A2-3 109 514, EP-B1-2 844 855, EP-A1-2 615 335, WO-A1-2019/016463 and EP-A2-1 114 949.

The purpose of a mechanical reduction gear is to change the speed and torque ratio between the input axis and the output axis of a mechanical system.

The new generations of bypass turbine engines, in particular turbine engines with high dilution rates, comprise a mechanical reduction gear that drives the shaft of a fan. Usually, the purpose of the reduction gear is to transform the “fast” rotational speed of a power turbine into a slower rotational speed for the shaft driving the fan.

This type of reduction gear comprises a central pinion, termed sun gear, a ring gear and pinions termed planet gears, the latter engaging between the sun gear and the ring gear. The planet gears are maintained by a chassis termed planet-carrier. The sun gear, the ring gear and the planet-carrier are planetary elements because their axes of revolution are the same as the longitudinal axis X of the turbine engine. Each planet gear has a different axis of revolution, evenly distributed over a single operating diameter around the axis of the planetary elements. These axes are parallel with the longitudinal axis X.

There are several reduction gear architectures. According to the state of the art in the field of bypass turbine engines, reduction gears are of the planetary or epicyclic type. In other similar applications, “differential” or compound architectures can be found.

-   -   In a planetary reduction gear, the planet carrier is fixed, and         the ring gear constitutes the output shaft of the device that         rotates in the opposite direction with respect to the sun gear.     -   In an epicyclic reduction gear, the ring gear is fixed, and the         planet-carrier constitutes the output shaft of the device that         rotates in the same direction as the sun gear.     -   In a differential reduction gear, no element is rotationally         fixed. The ring gear rotates in the opposite direction with         respect to the sun gear and the planet-carrier.

The reduction gears can comprise one or several gearing stages. This gearing is achieved in different ways, such as by contact, by friction and even by magnetic fields.

There are several types of contact gearing, such as straight, helical or herringbone gearings.

The present invention proposes to an improvement of a reduction gear with a simple, efficient and economical solution to improve the lubrication of its planet-carrier.

SUMMARY OF THE INVENTION

The Invention Features Several Aspects.

According to a first aspect, the invention relates to a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage, characterised in that it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, said first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part.

The invention thus proposes integrating a major portion of the lubrication circuits in the cage of the planet-carrier, which reduces the number of parts and facilitates the assembly of the reduction gear. Furthermore, the risks of oil leaks are thus greatly reduced.

The planet carrier according to the invention can comprise one or several of the following characteristics, taken individually or in combination:

-   -   said first and second inlets are oriented radially with respect         to said axis X and open radially outwards; they are thus easily         accessible for the purpose of connecting them to oil supply         means,     -   said first and second inlets are located in a same plane that is         perpendicular to said axis X and are at an angle with respect to         one another; they are therefore close to one another and can         pass through a same arm or through different arms of a crankcase         of the turbine engine wherein the reduction gear is integrated         with this planet-carrier,     -   said first and second chambers are arranged adjacent to one         another, one behind the other, along said axis X; this optimises         the compactness and therefore the dimensions of the lubrication         circuits,     -   one of said first and second chambers is located in said plane         and connected to one of said inlets by a radial and rectilinear         drill hole, and the other of said first and second chambers is         located outside of said plane and connected to the other of said         inlets by two drill holes, wherein a first drill hole being         located in said plane and a second drill hole extending at an         angle between the first drill hole and this other chamber; this         also optimises the compactness and therefore the dimensions of         the lubrication circuits; these open drills holes are preferably         sealed by plugs that can be screwed and/or glued.     -   said ducts are formed in one of said radial walls and extend in         a rectilinear manner between said first chamber and a         lubricating cores of the axes of the planet gears; the ducts are         thus formed in the thickness of the radial walls, or in excess         thickness provided in these walls,     -   said channels are formed in one of said radial walls and in said         cylindrical wall, and each is generally L-shaped, extending         between said second chamber and a projecting oil orifices         towards said gearings; the channels are thus formed in the         thickness of the radial and cylindrical walls, or in excess         thickness provided in these walls,     -   said first and second chambers are located on the inner         periphery of one of said radial walls, and are partially         delimited by this radial wall, and partially by an attached         annular distributor comprising a cylindrical wall delimiting,         internally, said chambers and at least an annular partition         axially closing one of said chambers,     -   one of said chambers is connected to at least one nozzle         spraying oil towards said sun gear, said nozzle being integrated         in said distributor; the nozzle is preferably configured to         project oil towards the coupling of the sun gear and its drive         shaft,     -   said second circuit further comprises channels supplying oil to         the gearings of the planet gears with the sun gear,     -   each of said first and second chambers has in cross-section a         general parallelepiped shape.

According to a second aspect, the invention relates to a planet-carrier for a mechanical reduction gear of a turbine engine, in particular of an aircraft, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls that are radial with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes for the passage of the gearings of the planet gears so that they may engage with a gearing of the ring gear, which is intended to extend around the planet gears and the cage, characterised in that it further comprises an annular distributor of lubricating oil which is formed of a single part and configured to be provided and secured to the inner periphery of one of said radial walls, so as to define, together with said radial wall, two annular chambers which are independent and sealed to oil circulation.

The manufacturing of the oil chambers is simplified since they are delimited between the cage, on one hand, and by the attached distributor, on the other hand. It is indeed easier and more cost-efficient to manufacture the distributor with casting operations or by machining a part, rather than manufacturing the chambers entirely on the cage, at the assembly site. The distributor has a general shape that is simple, and it is formed of a single part, which facilitates its mounting on the cage.

The planet-carrier according to the invention can comprise one or several of the following characteristics, taken individually or in combination:

-   -   said distributor comprises a cylindrical wall delimiting         internally said chambers and at least an annular partition         axially closing one of said chambers; the simply shaped         distributor can therefore be cheap to manufacture,     -   said distributor comprises two annular walls that extend         radially outwards from said cylindrical wall and that together         delimit one of said chambers, the other of said chambers being         delimited by one of these partitions and an annular surface         facing the radial wall on which the distributor is attached,     -   the or each partition comprises on its outer periphery an         external cylindrical centring surface on which is formed an         annular groove intended to receive an annular seal intended to         cooperate with the inner periphery of the radial wall on which         the distributor is attached; the cylindrical surfaces therefore         serve a dual purpose of centring but also of sealing, owing to         the fact that they are provided with seals that ensure that the         chambers, and therefore the lubrication circuits, are properly         sealed,     -   said cylindrical wall comprises a cylindrical centring surface         on which an annular groove is formed to receive an annular seal         intended to cooperate with the inner periphery of the radial         wall on which the distributor is attached; this cylindrical         surface also serves a dual centring and sealing purpose,     -   said first and second chambers are arranged adjacent to one         another, one behind the other, along said axis X,     -   said first and second chambers have each a cross-section that         has a general parallelepiped shape,     -   the distributor comprises a flange, or a fixation lugs onto said         cage, by means of screws,     -   an inner cylindrical surface of the inner periphery of said         radial wall on which the distributor is attached, comprises a         protruding annular rib configured to cooperate with said annular         seal,     -   an oil nozzle is connected to one of said chambers, and     -   the oil nozzle is integrated in the distributor, preferably on         said cylindrical wall.

The present invention also relates to a reduction gear for a turbine engine, in particular of an aircraft, comprising a sun gear mounted rotationally secure on a drive shaft around an axis of rotation X, a ring gear coaxial with the axis X and a plurality of planet gears arranged around the axis X, said planet gears being engaged with the sun gear and the annular ring gear that extends around the planet gears; said planet gears are movably mounted on the planet-carrier according to one of the features of the invention.

The drive shaft can be a low-pressure shaft of the turbine engine.

The present invention also relates to an aircraft turbine engine, characterised in that it comprises a mechanical reduction gear comprising a planet-carrier such as described above.

The characteristics of the different aspects of the invention can be combined with one another.

BRIEF DESCRIPTION OF THE FIGURES

Other characteristics and advantages will appear more clearly upon reading the following description of a non-limiting embodiment of the invention and with reference to the appended drawings, in which:

FIG. 1 is a schematic axial cross-section view of a turbine engine using the invention,

FIG. 2 is a partial view showing an axial cross-section of a mechanical reduction gear,

FIG. 3 is a schematic and perspective view of a mechanical reduction gear according to the invention,

FIG. 4 is a schematic axial cross-section view of the reduction gear of FIG. 3,

FIG. 5 is a partial, schematic and perspective view of an annular distributor of lubricating oil,

FIG. 6 is a schematic perspective view of the volumes of the lubricating oil circuits of the reduction gear of FIG. 3,

FIG. 7a is a schematic axial cross-section view of the reduction gear of FIG. 3, the cross-section being made in a plane,

FIG. 7b is another schematic axial cross-section view of the reduction gear of FIG. 3, the cross-section being made in a different plane, and

FIG. 7c is another schematic axial cross-section view of the reduction gear of FIG. 3, the cross-section being made in a different plane.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 describes a turbine engine 1 that comprises, conventionally, a fan S, a low-pressure compressor 1 a, a high-pressure compressor 1 b, an annular combustion chamber 1 c, a high-pressure turbine 1 d, a low-pressure turbine 1 e, and an exhaust pipe 1 h. The high-pressure compressor 1 b and the high-pressure turbine 1 d are connected by a high-pressure shaft 2 and form with the latter a high-pressure (HP) body. The low-pressure compressor 1 a and the low-pressure turbine 1 e are connected by a low-pressure shaft 3 and form with the latter a low-pressure (LP) body.

The fan S is driven by a fan shaft 4, which is driven with the LP shaft 3 by means of a reduction gear 6. The reduction gear 6 is generally of the planetary or the epicyclic type.

Although the following description relates to a planetary reduction gear or an epicyclic reduction gear, it also applies to a mechanical differential in which the three components, i.e. the planet-carrier, the ring gear and the sun gear are rotationally mobile, the rotation speed of one of these components depending in particular on the speed difference of the two other components.

The reduction gear 6 is positioned in the front part of the turbine engine. A fixed structure comprising schematically, in this case, an upstream part 5 a and a downstream part 5 b, constituting the engine crankcase or stator 5, is arranged to form an enclosure E around the reduction gear 6. This enclosure E is here closed in the upstream part by seals located at the level of a bearing and allowing the passage of the fan shaft 4, and in the downstream section by seals located at the level of the passage of the LP shaft 3.

FIG. 2 shows a reduction gear 6 that can have different architectures depending on whether some parts are fixed or rotating. At the inlet, the reduction gear 6 is connected to the LP shaft 3, for example by means of inner splines 7 a. The LP shaft 3 drives a planet pinion termed sun gear 7. Conventionally, the sun gear 7, of which the axis of rotation is the same as that of the turbine engine X, drives a series of pinions termed planet gears 8, these planet gears being evenly distributed over a single diameter around the axis of rotation X. This diameter is equal to twice the operating distance between the sun gear 7 and the planet gears 8. The number of planet gears 8 generally ranges from three to seven for this type of application.

The set of the planet gears 8 is held by a chassis termed planet-carrier 10. Each planet gear 8 rotates about its own axis Y and engages with the ring gear 9.

At the output, this provides:

-   -   in an epicyclic configuration, the planet gears 8 rotationally         drive the planet-carrier 10 about the axis X of the turbine         engine. The ring gear is secured to the engine crankcase or the         stator 5 by means of a ring-carrier 12 and the planet-carrier 10         is secured to the fan shaft 4.     -   in a planetary configuration, the planet gears 8 are held by a         planet-carrier 10 that is secured to the engine crankcase or the         stator 5. Each planet gear drives the ring gear, which is         supported on the fan shaft 4 by means of a ring-carrier 12.

Each planet gear 8 is mounted free to rotate by means of a bearing 11, for example a roller bearing or a hydrodynamic bearing. Each bearing 11 is mounted on one of the axes 10 b of the planet-carrier 10 and all the axes are positioned with respect to one another by means of one or several structural chassis 10 a of the planet-carrier 10. The number of axes 10 b and of bearings 11 is equal to the number of planet gears. For operating, assembly, manufacturing, control, repairs or replacement reasons, the axes 10 b and the chassis 10 a can be divided into several parts.

For the reasons mentioned above, the gearing of a reduction gear can be divided into several helices, each with a median plane P. In this example, we will detail the operation of a reduction gear with several helices and with a ring gear divided into two half-ring gears:

-   -   a front half-ring gear 9 a consisting of a rim 9 aa and an         attachment half-flange 9 ab. The rim 9 aa comprises the front         helix of the gearing of the reduction gear. This front helix         engages with that of the planet gear 8, which in turn engages         with that of the sun gear 7.     -   a rear half-ring gear 9 b consisting of a rim 9 ba and an         attachment half-flange 9 bb. The rim 9 ba comprises the rear         helix of the gearing of the reduction gear. This rear helix         engages with that of the planet gear 8, which in turn engages         with that of the sun gear 7.

In the case of herringbone gearings, if the helix widths vary between the sun gear 7, the planet gears 8, and the ring gear 9 because of overlapping gearings, they are all centred on a median plane P1 for the front helixes, and on another median plane P2 for the rear helixes. The other figures relate to the case of a bearing with two rows of rollers.

The attachment half-flange 9 ab of the front half-ring gear 9 a and the attachment half-flange 9 bb of the rear half-ring gear 9 b form the attachment flange 9 c of the ring gear. The ring gear 9 is secured to the ring-carrier 12 by assembling the attachment flange 9 c of the ring gear to the attachment flange 12 a of the ring-carrier by means of a bolted assembly for example.

The arrows of FIG. 2 show the path of the oil in the reduction gear 6. The oil arrives in the reduction gear 6 from the stator part 5 in a distributor 13 by different means that are not detailed in this view as they are specific to one or several types of architecture. The distributor 13 is divided into two parts, and generally each part has the same number of planet gears. The purpose of the injectors 13 a is to lubricate the gearings and the purpose of the arms 13 b is to lubricate the bearings. The oil is brought to the injector 13 a, exiting at its end 13 c to lubricate the gearings. The oil is also brought to the arm 13 b and circulates through the supply intake 13 d of the bearing. The oil then circulates through the axis 10 b or in one or several buffer zones 10 c to then exit through the orifices 10 d in order to lubricate the bearings 11 of the planet gears 8.

FIGS. 3 to 7 show an embodiment of a reduction gear 6 comprising several aspects of the invention.

One of these aspects relates to the lubricating oil distributor 13′ and another relates to the lubricating oil circuits 15 a, 15 b of the reduction gear 6.

The reduction gear 6 of the FIG. 5 and following is similar to that described above and comprises a planet-carrier 10 attached with a cage 14.

The cage 14 comprises two radial annular walls 14 a, 14 b that extend around the axis X, these walls 14 a, 14 b being parallel and being respectively a front radial wall 14 a and a rear radial wall 14 b. The walls 14 a, 14 b are connected to one another at their outer peripheries by a cylindrical wall 14 c. The walls 14 a, 14 b and 14 c are more visible in FIGS. 7a to 7 c.

The cage 14 defines an internal housing intended to receive the central sun gear 7 with an axis of rotation X, and the annular row of planet gears 8 arranged around the sun gear 7.

At least one of the radial walls 14 a, 14 b (the front wall 14 a in the example shown in FIGS. 7a to 7c ) comprises orifices 14 aa for mounting the axes 10 b of the planet gears 8, and the cylindrical wall 14 c comprises through-holes 14 c a for the passage of the gearings of the planet gear 8 so that they may engage with the gearing of the ring gear 9 intended to extend around the planet gears 8 and the cage 14.

The orifices 14 aa are regularly distributed about the axis X. Each of the walls 14 a, 14 b further comprises a central orifice 14 ab, 14 ba aligned with the axis X. The walls 14 a, 14 b can further be connected to one another by another cylindrical wall 14 d extending over the inner periphery of the walls 14 a, 14 b, around the orifices 14 ab, 14 ba. This wall 14 d is visible in FIG. 7 b.

The reduction gear 6 comprises two lubrication circuits 15 a, 15 b that are independent, the oil volumes of these circuits being visible in FIG. 6.

The first circuit 15 a comprises a first oil inlet 15 aa connected by a first annular oil chamber 15 ab extending about the axis X to ducts 15 ac supplying oil to the axes 10 b of the planet gears 8.

The second circuit 15 b comprises a second oil inlet 15 ba connected by a second annular oil chamber 15 bb extending about the axis X to channels 15 bc supplying oil to the gearings of the planet gears 8 with the ring gear 9. The second circuit 15 b can further comprise channels 15 bd supplying oil to the gearings of the planet gears 8 with the sun gear 7.

As can be seen in the drawings, the inlets 15 aa, 15 ba, the ducts 15 ac, the channels 15 bc, 15 bd, and at least a portion of the chambers 15 ab, 15 bb are integrated in the cage 15, i.e. they are not formed by or in the parts attached on the cage but are an integral part of the cage.

The inlets 15 aa, 15 ba are oriented radially with respect to said axis X and open radially outwards for the purpose of their connection to oil supply means. These inlets 15 aa, 15 ba are located in a same plane P3, perpendicular to the axis X and at an angle with respect to one another in this plane P3, about the axis X (FIGS. 7a and 7b ).

The chambers 15 ab, 15 bb are arranged adjacent to one another, one behind the other, along said axis X. They each have a general parallelepiped shape in the example shown. One of these chambers, specifically the front chamber 15 bb in the example shown, is located in the abovementioned plane P3 and is connected to the inlet 15 ba by a radial and rectilinear drill hole 16 a formed in the rear radial wall 14 b (FIGS. 7b and 7c ). The other chamber 15 ab is located outside of the plane P3 (in this case behind the plane) and is connected to the other inlet 15 aa by two drill holes, a first drill hole 16 b being located in the plane P3 and a second drill hole 16 c extending at an angle from the first drill hole 16 b to the chamber 15 ab (FIG. 7a ).

The ducts 15 ac are formed in the rear radial wall 14 b and extend in a rectilinear manner and at a slight angle between the chamber 15 ab and the cores 17 supplying oil to the planet gears 8 (FIG. 7a ).

The channels 15 bc are formed in the rear radial wall 14 b and in the cylindrical wall 14 c (FIG. 7c ). They each have a general L shape and each comprises a rectilinear and radial branch that extends in the wall 14 b from the chamber 15 bb, and an axial rectilinear branch extending in the wall 14 c to the orifices 15 bc 1 projecting oil towards the gearings of the planet gears 8 with the ring gear 9 (FIGS. 7c and 6).

The channels 15 bd are formed in the wall 14 d and extend from the chamber 15 bb to the orifices 15 bd 1 for projecting oil towards the gearings of the planet gears 8 with the sun gear 7 (FIGS. 6 and 7 b).

The chambers 15 ab, 15 bb are located at the inner periphery of the wall 14 b, and are partially delimited by this radial wall, and partially by the distributor 13′ attached on this wall and secured thereto by means of screws 18 (FIGS. 3 and 4).

The inner periphery of the wall 14 b comprises a cylindrical wall 19 oriented towards the rear and comprising an internal cylindrical surface 19 a on which open the radially internal ends of the drill holes 16 a, 16 c, of the ducts 15 ac, and of the channels 15 bc (FIGS. 7a to 7c ). A rear radial surface 19 b of the wall 14 b extends from the central orifice 14 bb of the wall 14 b to the surface 19 a. The channels 15 bd open axially in the downstream direction onto the surface 19 b (FIG. 7b ).

The distributor 13′ has a generally annular shape and is formed of a single part. It comprises a cylindrical wall 13 a delimiting internally the chambers 15 ab, 15 bb, the chambers being intended to be delimited externally by the surface 19 a of the wall 14 b when the distributor 13′ is mounted coaxially on the wall 14 b by engaging it inside the edge and the orifice 14 bb of the wall 14 b.

The distributor 13′ comprises two annular partitions 13 b, 13 c that are substantially radial in the example shown. One of the partitions 13 c extends radially outwards from the rear end of the wall 13 a and is supported radially, in a sealed manner, by the surface 19 a, here at the rear end of the edge 19.

Thy cylindrical wall 13 a of the distributors 13′ has a front end that is supported radially, in a sealed manner, by the peripheral edge of the orifice 14 bb. The partition 13 b extends radially outwards, at a distance from the upstream end of the wall 13 a and of the partition 13 b, and is also supported radially, in a sealed manner, by the surface 19 a.

Each sealed support is achieved, in the example shown, by an O-ring that is arranged in an annular groove 20 of the outer periphery of the partition 13 b, 13 c, or of the front end of the wall 13 a, and that cooperates by support and elastic deformation with the radial wall 14 b or its edge 19.

To facilitate the centring of the distributor 13′ and the forming of grooves 20 on the partitions 13 b, 13 c, the latter can be oversized at their outer peripheries and each can comprise a centring cylindrical surface on which is formed the groove 20 receiving a seal. Furthermore, to facilitate the mounting of the distributor 13′ by an axial translational movement in the orifice 14 bb and the edge 19, the seal supported by the partition 13 b can cooperate with an annular rib 19 d protruding on the surface 19 a, as can be seen in FIGS. 7b and 7 c.

It should be understood that the chamber 15 bb is closed by the distributor 13′ and delimited between a front annular portion of the surface 19 a, the surface 19 b, a front annular portion of the wall 13 a, and the partition 13 c. The chamber 15 ab is closed by the distributor 13′ and delimited between a rear annular portion of the surface 19 a, a rear annular portion of the wall 13 a, and the partition 13 b, 13 c.

The chambers 15 ab, 15 bb are independent since they do not communicate with one another.

The distributor 13′, and in particular its partition 13 b, comprise an annular flange 21 that extends radially outwards and comprises orifices 22 for the passage of screws 18 that are screwed into the tapped orifices of the wall 14 b of the cage.

The distributor 13′ further comprises, protruding on the internal cylindrical surface of its wall 13 a, an oil nozzle 23 that is connected to the front chamber 15 bb (FIGS. 5 and 7 a). This nozzle 23 is configured to project oil on the coupling of the sun gear 7 and the low-pressure shaft 3 of FIG. 2.

The nozzle 23 is also advantageously integrated in the distributor 13′, as can be seen in the example shown.

The oil circuits 15 a, 15 b are advantageously configured to be fluidly, connected at the level of their inlets and their possible outlets, by male-female fittings, i.e. by connections that only require fitting along an axial direction of motion of a male connector into a female connector. Even if a connector is presented in the following description as being male and intended to engage with a female connector, it can alternatively be replaced by a female connector intended, therefore, to engage with a male connector, and conversely. The sealing of the male-female connectors can be provided by O-rings or similar seals.

With regard to the inlets 15 aa, 15 ba, each one comprises a female connector in the example shown, intended to receive the male connector of an oil supply pipe (FIGS. 6 to 7 c).

Regarding the oil outlets, excluding the orifices 15 bc 1, 15 bd 1 for the projection of oil, they are located at the radially external ends of the ducts 15 ac (FIGS. 6 and 7 a).

As can be seen in FIG. 7a , each of the outlets of the ducts 15 ac comprises a female connector 15 ac 1 in the example shown, intended to receive the male connector of one of the cores 17. These connectors 15 ac 1 are oriented axially, all in the same direction, which here is forwards.

The purpose of the cores 17 is to lubricate and cool the axes 10 b of the planet gears 8.

In the example embodiment shown, each axis 10 b is guided by a double roller bearing 11, i.e. with double rows of rollers 11 a. The two rows extend about a single axis that corresponds to the axis, marked Y of the axis 10 b of the planet gear 8. The application can also comprise more than two rows.

Conventionally, the rollers are guided in tracks defined by inner and outer rings. A feature here is that the inner rings for guiding the rollers 11 a are integrated in the axis 10 b. The outer periphery of the axis 10 b therefore comprises cylindrical tracks 11 b for the rolling of the rollers 11 a, each track 11 b being axially delimited by annular ribs 11 c, the purpose of which is to guide the cages 11 d maintaining the rollers 11 a. Furthermore, FIGS. 7a to 7c show that the outer rings are integrated at the inner periphery of the planet gears 8. The inner periphery of the planet gears 8 thus comprises cylindrical tracks 8 a for rolling the rollers 11 a.

The inner periphery of the axis 10 b comprises an internal cylindrical surface 10 e intended to be covered by the core 17.

This core 17 essentially comprises three parts, i.e. a cylindrical portion 17 a, a disc 17 b and a ring 17 c. The core 17 is in this case formed from a single part, but this characteristic is not limiting.

The portion 17 a extends along the axis Y and comprises an inner duct, termed first duct 17 a 1, that extends along the axis Y over nearly the entire length of the portion 17 a in the example shown.

The portion 17 a has an axial (rear) end forming the abovementioned male connector, and an opposite end (front) connected to the centre of the disc 17 b, the outer periphery of which is connected to the ring 17 c. The disc 17 b extends in a plane that is substantially perpendicular to the axis Y and comprises an inner duct, termed second duct 17 b 1, that extends radially from the first duct 17 a 1 to the external annular surface of the disc 17 b.

The disc 17 b is substantially connected to the middle of the ring 17 c (along the axis Y), so that the second duct substantially opens onto the middle of the ring 17 c. The disc 17 b could comprise several second radial ducts 17 b 1 regularly spaced about the axis Y.

The ring 17 c extends about the axis Y and delimits with the internal cylindrical surface of the axis 10 b an annular cavity 22 for the circulation of oil and for the supply of the orifices 10 d transporting the oil to the bearing 11 and to the cages 11 d, these orifices being visible in FIG. 2.

In use, the oil reaches the chambers 15 ab, 15 bb through the inlets 15 aa, 15 ba and the drill holes 16 a, 16 b and 16 c. The oil in the chamber 15 ab supplies the cores 17 through the ducts 15 ac for the purpose of lubricating the bearing 11. The oil in the chamber 15 bb supplies the channels 15 bc, 15 bd for the purpose of lubricating the gearings. Oil is further projected by the nozzle 23 onto the coupling of the sun gear 7 with the LP shaft 3. 

The invention claimed is:
 1. A planet-carrier for a mechanical reduction gear of a turbine engine, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of a ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part.
 2. The planet-carrier according to claim 1, wherein said first and second inlets are oriented radially with respect to said axis X and open radially outwards.
 3. The planet-carrier according to claim 2, wherein said first and second inlets are located in a same plane that is perpendicular to said axis X and are at an angle with respect to one another.
 4. The planet-carrier according to claim 1, wherein said first and second chambers are arranged adjacently, one behind the other, along said axis X.
 5. The planet-carrier according to claim 3, wherein one of said first and second chambers is located in said plane and connected to one of said inlets by a radial and rectilinear drill hole, and the other of said first and second chambers is located outside of said plane and connected to the other of said inlets by two drill holes, wherein a first drill hole being located in said plane and a second drill hole extending at an angle between the first drill hole and the other chamber, and wherein said first and second chambers are arranged adjacently, one behind the other, along said axis X.
 6. The planet-carrier according to claim 1, wherein said ducts are formed in one of said radial walls and extend in a rectilinear manner between said first chamber and a lubricating core of said axes of the planet gears.
 7. The planet-carrier according to claim 1, wherein said channels are formed in one of said radial walls as well as in said cylindrical wall and each has a general L shape extending between said second chamber and the orifices projecting oil towards said gearings.
 8. The planet-carrier according to claim 1, wherein said first and second chambers are located on the inner periphery of one of said radial walls, and are partially delimited by this radial wall, and partially by an attached annular distributor comprising a cylindrical wall delimiting, internally, said chambers and at least an annular partition axially closing one of said chambers.
 9. The planet-carrier according to claim 8, wherein one of said chambers is connected to at least one nozzle spraying oil towards said sun gear, said nozzle also being integrated in said distributor.
 10. The planet gear according to one claim 1, wherein said first and second chambers each have in cross-section a general parallelepiped shape.
 11. The planet-carrier according to claim 1, wherein said second circuit further comprises channels supplying oil to the gearings of the planet gears with the sun gear.
 12. A reduction gear for a turbine engine, comprising a sun gear mounted rotationally secure on a drive shaft around an axis of rotation X, an annular ring gear coaxial with the axis X and a plurality of planet gears arranged around the axis X, said planet gears being engaged with the sun gear and the annular ring gear that extends around the planet gears, wherein said planet gears are mounted mobile on the planet-carrier according to claim
 1. 13. A turbine engine of an aircraft comprising a mechanical reduction gear comprising a planet-carrier according to claim
 1. 14. A planet-carrier for a mechanical reduction gear of a turbine engine, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of a ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part, and wherein said first and second inlets are oriented radially with respect to said axis X and open radially outwards.
 15. A planet-carrier for a mechanical reduction gear of a turbine engine, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of a ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part, wherein said first and second inlets are located in a same plane that is perpendicular to said axis X and are at an angle with respect to one another, wherein one of said first and second chambers is located in said plane and connected to one of said inlets by a radial and rectilinear drill hole, and the other of said first and second chambers is located outside of said plane and connected to the other of said inlets by two drill holes, wherein a first drill hole being located in said plane and a second drill hole extending at an angle between the first drill hole and the other chamber, and wherein said first and second chambers are arranged adjacently, one behind the other, along said axis X.
 16. A planet-carrier for a mechanical reduction gear of a turbine engine, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of a ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part, and wherein said channels are formed in one of said radial walls as well as in said cylindrical wall and each has a general L shape extending between said second chamber and the orifices projecting oil towards said gearings.
 17. A planet-carrier for a mechanical reduction gear of a turbine engine, said planet-carrier comprising a cage defining an internal housing intended to receive a central sun gear with an axis of rotation X, and an annular row of planet gears arranged around the sun gear, said cage comprising two annular radial walls with respect to said axis X, and connected to one another at their outer periphery by a cylindrical wall of axis X, at least one of these radial walls comprising a mounting orifices of the axes of said planet gears, and the cylindrical wall comprising through-holes of the passage of the gearings of the planet gears so that they may engage with a gearing of a ring gear, which is intended to extend around the planet gears and the cage, wherein it comprises first and second independent lubrication circuits, the first circuit comprising a first oil inlet connected by a first annular oil chamber extending around the axis X to ducts supplying oil to said axes of the planet gears, and the second circuit comprising an second oil inlet connected by a second annular oil chamber extending around the axis X to channels supplying oil to the gearings of the planet gears with the ring gear, and in that said cage, first and second inlets, said ducts, said channels and at least a portion of said first and second chambers are formed of a single part, wherein said first and second chambers are located on the inner periphery of one of said radial walls, and are partially delimited by this radial wall, and partially by an attached annular distributor comprising a cylindrical wall delimiting, internally, said chambers and at least an annular partition axially closing one of said chambers. 